This invention relates to self-excited generators, and more particularly to improvements in or to self-excited generators of the concentrated winding type.
Conventional self-excited generators include a concentrated winding type in which an output coil and an exciting coil are wound on the stator in such a concentrated manner as to produce respective electromotive forces in the same phase, while a field coil is wound on the rotor to be supplied with exciting current from the exciting coil.
According to such type self-excited generators, since the output coil and the exciting coil are wound on the stator so as to be located in the same magnetic circuit, the output voltage of the output coil can temporarily drop when the output is temporarily brought into a nearly shorted state due to its connection with a load having small starting resistance such as an electric motor and a lamp, so that the output voltage of the exciting coil accordingly drops to reduce exciting current supplied to the field coil. This reduced supply of exciting current in turn causes a further drop in the output voltage of each of the output coil and the exciting coil, making the load difficult to start its operation, or prolonging the time before the load exhibits its rated performance. The above-mentioned drop in the output voltage of the output coil is due to a decrease in the magnetic flux passing in a magnetic circuit formed between the rotor and the stator, which occurs when the output of the self-excited generator is brought into a nearly shorted state.